Various systems and devices such as, for example, optical test instruments and equipment, include one or more optical elements, which may be provided to implement, for example, optical filtering. In some of these systems, it may be desirable to simultaneously switch one or more optical elements into and out of an optical path. Preferably, this optical element switching operation is performed relatively rapidly.
In the past, rapid and simultaneous optical element switching has been accomplished using, for example, a wheel mechanism that is configured to rotate the optical elements into and out of the optical path. In one exemplary wheel mechanism embodiment, the optical elements are arranged around the perimeter of a wheel. As different optical elements are to be moved into and out of the optical axis, a motor or other driver rotates the wheel, stopping when the desired optical element is in the optical path.
Although wheel mechanisms generally operate safely, these mechanisms also suffer certain disadvantages. For example, the configuration of many of these wheel mechanisms provides for sequential, rather than random, access to the elements at the edges of the wheel. As a result, the amount of time and energy that may be used to switch one element into the optical path and another optical element out of the optical path can be undesirably high. This may be most pronounced when the wheel is used to move optical elements into and out of the optical path that are located on opposite sides of the wheel.
Another drawback of some known wheel mechanisms is that rapid movement of the wheel can cause disturbances in the system. These disturbances can result in, for example, image blur. This can be a significant factor in applications that implement precise optical system control such as, for example, in satellite applications. To compensate for the disturbances a rapidly moving wheel may cause, some systems may implement long settling periods after wheel movement. Other systems may use complex force compensation and/or isolation mechanisms, which can increase the system complexity and, in some cases, simultaneously decrease system reliability. Moreover, some of these complex mechanisms may also dissipate significant power, which can negatively impact the thermal profile of the system.
To overcome one or more of the above-noted drawbacks, switch assemblies, such as those disclosed in the applications cross-referenced above, have been developed. These switch assemblies also operate safely and reliably, yet suffer additional drawbacks. In particular, each of the switch assemblies disclosed in these applications rotates via a spring biased pivot mechanisms, such as a torsion bar spring, and is magnetically latched in one of two rotational positions. The strength of the magnetic field that is used to overcome the torsion bar spring force and pull the switch into a latched position may be of such a magnitude that a relatively high latching force is applied to the switch assembly. This can create comparatively high contact forces, which can result in unwanted shock and vibrations upon latching. In addition, substantial power may be needed to overcome the magnetic force to disengage the switch assembly from a latched position.
Hence, there is a need for a switch assembly that addresses one or more of the above-noted drawbacks. Namely, a switch assembly that does not generate latching forces that result in unduly high shock and vibration, and/or a switch assembly that uses less power to release the switch from a latched position The present invention addresses one or more of these needs.